Profiles September 1987

it's a pizza-pie chart

Bar chart, pie chart, scatter plot, line chart, area chart; what are you going to use to visualize your data? In this post, I'm going to talk about different types of data visualizations, and when each is well suited for your purposes.

Bar Chart

Bar charts are good for showing basic size comparisons, especially among large numbers of objects. The length of the bar indicates the size of your statistic. As with all types of charts, the length of each bar should correspond mathematically to the data it represents. In other words, good data visualization is not just eyeballed; it's measured. 

Pie Chart

Pie charts are good for showing the comparisons of how a certain piece of data breaks down into different groups. You use pie charts when the sum of all the parts adds up to 100%. There are many variations of pie charts out there, including donut charts, which are essentially pies with holes. The danger with pie charts is at a certain point, it's difficult for the human eye to compare the differences in the angles of the pie. They work great for large, obvious comparisons, but not as great for more subtle ones

Scatter Plot

Scatter plots are what you used to do in math class. You have two axes; vertical, and horizontal, and you draw a point where your piece of data appears at both axes. When you draw many points of data, you can achieve a scatter effect, and use it to spot trends. These are effective graphs if you're trying to illustrate a trend among an enormous set of data. 

Line Graph

Line graphs are essentially scattered plots with lines connecting the elements. Typically, you use line graphs with set intervals on one of the axes; most often using time on the bottom axis. These are good for illustrating trend data as well. Sometimes line graphs are filled in, and become area charts. 

Area Chart